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N Howes

Publications and source records attributed to N Howes.

15 recordsLinked to original sources
PubMed2005

Anticipation in familial pancreatic cancer.

BACKGROUND: Previous studies of anticipation in familial pancreatic cancer have been small and subject to ascertainment bias. Our aim was to determine evidence for anticipation in a large number of European families. PATIENTS AND METHODS: A total of 1223 individuals at risk from 106 families (264 affected individuals) were investigated. Generation G3 was defined as the latest generation that included any individual aged over 39 years; preceding generations were then defined as G2 and G1. RESULTS: With 80 affected child-parent pairs, the children died a median (interquartile range) of 10 (7, 14) years earlier. The median (interquartile range) age of death from pancreatic cancer was 70 (59, 77), 64 (57, 69), and 49 (44, 56) years for G1, G2, and G3, respectively. These indications of anticipation could be the result of bias. Truncation of Kaplan-Meier analysis to a 60 year period to correct for follow up time bias and a matched test statistic indicated significant anticipation (p=0.002 and p<0.001). To minimise bias further, an iterative analysis to predict cancer numbers was developed. No single risk category could be applied that accurately predicted cancer cases in every generation. Using three risk categories (low with no pancreatic cancer in earlier generations, high with a single earlier generation, and very high where two preceding generations were affected), incidence was estimated without significant error. Anticipation was independent of smoking. CONCLUSION: This study provides the first strong evidence for anticipation in familial pancreatic cancer and must be considered in genetic counselling and the commencement of secondary screening for pancreatic cancer.

Adult↗
PubMed2005

Surgery in the treatment of acute pancreatitis--minimal access pancreatic necrosectomy.

Between 5% and 10% of patients with acute pancreatitis will develop infected pancreatic necrosis. Traditional open surgery for this condition carries a mortality rate of up to 50%, and therefore a number of less invasive techniques have been developed, including radiological drainage and a minimal access retroperitoneal approach. No randomised controlled trials have been published which compare these techniques. Indications for minimal access surgery are the same as for open surgery, i.e. infected pancreatic necrosis or failure to improve with extensive sterile necrosis. Access is obtained to the pancreatic necrosis via the left loin and necrosectomy performed using an operating nephroscope, and this often requires several procedures to remove all necrotic tissue. The cavity is continuously irrigated on the ward in between procedures. The results of this approach are encouraging, with less systemic upset to the patient, a lower incidence of post-operative organ failure when compared with open surgery, and a reduced requirement for ITU support. There is also a trend towards a lower mortality rate, although this does not reach statistical significance on the data published so far. Current evidence suggests that a minimal access approach to pancreatic necrosis is feasible, well tolerated and beneficial for the patient when compared with open surgery.

Dilatation↗
PubMed2002

The N34S mutation of SPINK1 (PSTI) is associated with a familial pattern of idiopathic chronic pancreatitis but does not cause the disease.

BACKGROUND: Mutations in the PRSS1 gene explain most occurrences of hereditary pancreatitis (HP) but many HP families have no PRSS1 mutation. Recently, an association between the mutation N34S in the pancreatic secretory trypsin inhibitor (SPINK1 or PSTI) gene and idiopathic chronic pancreatitis (ICP) was reported. It is unclear whether the N34S mutation is a cause of pancreatitis per se, whether it modifies the disease, or whether it is a marker of the disease. PATIENTS AND METHODS: A total of 327 individuals from 217 families affected by pancreatitis were tested: 152 from families with HP, 108 from families with ICP, and 67 with alcohol related CP (ACP). Seven patients with ICP had a family history of pancreatitis but no evidence of autosomal dominant disease (f-ICP) compared with 87 patients with true ICP (t-ICP). Two hundred controls were also tested for the N34S mutation. The findings were related to clinical outcome. RESULTS: The N34S mutation was carried by five controls (2.5%; allele frequency 1.25%), 11/87 (13%) t-ICP patients (p=0.0013 v controls), and 6/7 (86%) affected (p<0.0001 v controls) and 1/9 (11%) unaffected f-ICP cases. N34S was found in 4/108 affected HP patients (p=0.724 v controls), in 3/27 (11%) with wild-type and in 1/81 (1%) with mutant PRSS1, and 4/67 ACP patients (all p>0.05 v controls). The presence of the N34S mutation was not associated with early disease onset or disease severity. CONCLUSIONS: The prevalence of the N34S mutation was increased in patients with ICP and was greatest in f-ICP cases. Segregation of the N34S mutation in families with pancreatitis is unexplained and points to a complex association between N34S and another putative pancreatitis related gene.

Adult↗
PubMed2001

A new polymorphism for the RI22H mutation in hereditary pancreatitis.

BACKGROUND AND AIMS: Hereditary pancreatitis (HP) is a rare form of recurrent acute and chronic pancreatitis. Mutations in the cationic trypsinogen (protease serine 1, PRSS1) gene have been identified as causing HP. The R122H (previously known as R117H) mutation is the commonest and can be detected by a single and rapid polymerase chain reaction/restriction fragment length polymorphism (PCR/RFLP) based technique using the AflIII enzyme. This test however may give a false negative result in the presence of a neutral polymorphism within the enzyme recognition site. The frequency of this event was examined by sequencing studies in patients with HP and in healthy controls. METHODS: Of 60 families identified by the UK and Ireland consortium of EUROPAC (European Registry for Hereditary Pancreatitis and Familial Pancreatic Cancer), 51 were screened for R122H, N29I, and A16V mutations using standard techniques, and by sequencing of all five exons of cationic trypsinogen. RESULTS: Twelve families had the N29I mutation, one family had A16V and, on standard testing, 15 families had the R122H mutation. An additional family with the R122H mutation was found on direct sequencing. The false negative result was due to a neutral polymorphism C-->T at the third base of the codon, not affecting the amino acid coded for, destroying the AflIII restriction site. This polymorphism was not observed in 50 DNA specimens (100 chromosomes) from controls nor from 50 individuals from PRSS1 mutation negative HP families. A novel mutation specific PCR was developed to avoid this pitfall. CONCLUSIONS: One of the 16 families with HP and an R122H mutation contained a polymorphism affecting the AflIII restriction site. Adoption of an alternative R122H assay is important for genetic studies in individuals with apparent HP.

Acute Disease↗
PubMed2001

Molecular diagnosis of early pancreatic ductal adenocarcinoma in high-risk patients.

The prevalence of pancreatic cancer in the general population is too low--even in high-prevalence areas such as Northern Europe and North America (8-12 per 10(5) population)--relative to the diagnostic accuracy of present detection methods to permit primary screening in the asymptomatic adult population. The recognition that the lifetime risk of developing pancreatic cancer for patients with hereditary pancreatitis (HP) is extremely high (20% by the age of 60 years and 40% by the age of 70 years) poses considerable challenges and opportunities for secondary screening in those patients without any clinical features of pancreatic cancer. Even for secondary screening, the detection of cancer at a biological stage that would be amenable to cure by surgery (total pancreatectomy) still requires diagnostic modalities with a very high sensitivity and specificity. Conventional radiological imaging methods such as endoluminal ultrasound and endoscopic retrograde pancreatography, which have proved to be valuable in the early detection of early neoplastic lesions in patients with familial pancreatic cancer, may well be applicable to patients with HP but only in those without gross morphological features of chronic pancreatitis (other than parenchymal atrophy). Unfortunately, most cases of HP also have associated gross features of chronic pancreatitis that are likely to seriously undermine the diagnostic value of these conventional imaging modalities. Pre-malignant molecular changes can be detected in the pancreatic juice of patients. Thus, the application of molecular screening in patients with HP is potentially the most powerful method of detection of early pancreatic cancer. Although mutant (mt) K-ras can be detected in the pancreatic juice of most patients with pancreatic cancer, it is also present in patients with non-inherited chronic pancreatitis who do not progress to pancreatic cancer (at least in the short to medium term), as well as increasingly in the older population without pancreatic disease. Nevertheless, the presence of mt-K-ras may identify a genuinely higher-risk group, enabling additional diagnostic imaging and molecular resources to be focussed on such a group. What is clear is that prospective multi-centre studies, such as that being pursued by the European Registry of Hereditary Pancreatitis and Familial Pancreatic Cancer (EUROPAC), are essential for the development of an effective secondary screening programme for these patients.

Biomarkers, Tumor↗
PubMed2000

Screening for early pancreatic ductal adenocarcinoma in hereditary pancreatitis.

Patients with hereditary pancreatitis have a 40% lifetime risk of developing pancreatic ductal adenocarcinoma. Existing methods of diagnosing pancreatic cancer such as tumor markers, endoscopy, and radiological imaging lack the sensitivity and specificity for early diagnosis, particularly in a background of chronic pancreatitis. Molecular based strategies offer new avenues of screening for pancreatic ductal adenocarcinoma in these high-risk patients, which may allow the development of highly sensitive and specific diagnostic tests for the early detection of cancer.

Adenocarcinoma↗
PubMed1999

Adjuvant therapy for pancreatic cancer.

Pancreatic cancer is a major cause of cancer death; and despite advances in the standards of surgery and supportive care, the median and long-term survival rates have not shown similar dramatic improvements. Techniques such as radical surgery alone cannot guarantee a cure. Previous work with conventional chemotherapy and radiotherapy in patients with advanced pancreatic cancer has indicated a role for adjuvant therapy for patients with resectable tumors. The main modalities that have been assessed are based on the Gastrointestinal Tumour Study Group (GITSG) results using 5-fluorouracil chemotherapy, external beam radiation therapy (EBRT), or both. Alternative approaches such as neoadjuvant therapy have been used, which may increase the number of patients suitable for resection; and regional therapy techniques have been used to increase the therapeutic potential by concentrating agents to the tumor bed. The results of single or combination therapy do show some improvement in survival but have been limited in most cases to retrospective nonrandomized series of patients. Therefore the results must be assessed as such. There are several large randomized trials that will deliver definitive answers in the near future as to whether conventional adjuvant therapy is effective. New approaches using novel agents for advanced disease are currently being assessed, and they may eventually identify the most appropriate and effective agents to use for pancreatic cancer in the adjuvant setting.

Antimetabolites, Antineoplastic↗
PubMed1997

Hereditary pancreatitis and familial pancreatic cancer.

Important advances in the understanding of pancreatic diseases have taken place through the application of molecular methods in the study of the inherited form of pancreatitis and pancreas cancer. Mutations of the cationic trypsinogen gene have been found to be causative for hereditary pancreatitis with important implications for the molecular pathogenesis of acute and chronic pancreatitis. A variety of cancer syndromes involving the P16 and BRCA2 genes, for example, also lead to pancreatic cancer, but the gene responsible for familial pancreatic cancer has not been identified so far. The establishment of a European Registry of Hereditary Pancreatitis and Pancreatic Cancer (EUROPAC) will facilitate future developments.

Family Health↗
PubMed1997

Surgical practice is evidence based.

BACKGROUND: The quality of surgical research, and particularly the reluctance of surgeons to perform randomized controlled trials, has been criticized. The proportion of surgical treatments supported by satisfactory scientific evidence has not been evaluated previously. METHODS: A 1-month prospective audit was performed of 100 surgical inpatients admitted under two consultants in a general surgical/vascular unit at an urban teaching hospital; the main illness and interventions were agreed through group discussions in each case. The literature concerning the efficacy of each treatment was reviewed, and the evidence was categorized as: (1) supported by randomized controlled trial evidence; (2) sufficient other evidence of efficacy to make a placebo-controlled trial unethical; or (3) neither of the above. RESULTS: Of the 100 patients studied, 95 (95 per cent confidence interval (c.i.) 89-98) received treatment based on satisfactory evidence (categories 1 and 2) and, of these, 24 patients (95 per cent c.i. 17-35) received treatments based on randomized controlled trial evidence and 71 had treatments based on other convincing evidence (95 per cent c.i. 62-80). CONCLUSION: Inpatient general surgery is 'evidence based', but the proportion of surgical treatments supported by randomized controlled trial evidence is much smaller than that found in general medicine. Some reasons for this are clear, but the extent to which surgical practice needs to be reevaluated is not. Current methods for classifying and describing evidence in therapeutic studies need improvement.

Emergencies↗
PubMed1994

Hyaluronan binding function of CD44 is transiently activated on T cells during an in vivo immune response.

Though CD44 functions as a cell surface receptor for hyaluronan (HA) in some cell lines, most normal hematopoietic cells expressing CD44 do not bind HA. Certain CD44-specific monoclonal antibodies (mAbs) can rapidly induce CD44-mediated HA binding in normal murine T cells. This observation suggests that in vivo mechanisms may exist for activating the HA receptor function of CD44 on normal T cells. Here, it is shown that up to one third of splenic T cells are capable of CD44-mediated binding of fluorescein-conjugated HA (Fl-HA) during an in vivo allogeneic response. HA binding activity peaks at 7-8 d postinjection and declines rapidly. These rapid kinetics could be the result of transient activation of CD44 function and/or differentiation or expansion of short-lived population(s) that have constitutive HA-binding function. Both CD4 and CD8 T cells are included in the HA binding population which is strongly CD44 positive. After separation of HA-binding cells from nonbinding cells by cell sorting, it is shown that almost all cytotoxic effector cells are found in the HA-binding population. However, there is no evidence that CD44-mediated HA recognition is directly involved in the killing of target cells, since cytotoxicity could not be inhibited by CD44-specific mAbs that inhibit HA binding or by soluble HA. PCR amplification of cDNA reverse transcribed from RNA of sorted HA-binding cells indicated no evidence for CD44 isoforms other than the standard (hematopoietic) form. Though CD44 expression is known to be elevated upon T cell activation, and, as shown here, HA-binding function is induced in a portion of CD44-expressing T cells including cytotoxic effector cells, the role of CD44 and HA-recognition in immune responses is not known.

Animals↗
PubMed1982

Purification and properties of guanine, queuine-tRNA transglycosylase from wheat germ.

Guanine, queuine-tRNA transglycosylase has been purified from wheat germ to homogeneity. The specific activity is 2,000 pmol h-1 mg-1 of protein. The enzyme has an apparent Mr = 140,000. It migrates as a single band with Mr = 68,000 on electrophoresis in sodium dodecyl sulfate gels, indicating two Mr = 68,000 subunits. Both guanine (Km = 6.0 X 10(-8) M) and queuine (KI = 9.5 X 10(-8) M) are substrates but 7-(aminomethyl)-7-deazaguanine is not. The enzyme requires a monovalent or a divalent cation; Na+ and Mg2+ are more effective activators than other cations. The optimum pH is 7.6. Six tRNA isoacceptors found in wheat germ are substrates for the enzyme.

Animals↗
PubMedDate not supplied

Molecular pathogenesis of pancreatic ductal adenocarcinoma and clinical implications.

Pancreatic ductal adenocarcinoma (PDAC) is a significant cause of cancer death worldwide. PDAC is also one of the best-studied cancers with regard to molecular pathogenesis. The chief risk factors associated with PDAC are smoking and pancreatitis, in addition genetic predisposition seems to play a major role. This genetic predisposition may in some cases be indirect, for example via the elevated risk of pancreatitis seen in patients with hereditary pancreatitis (HP). The elucidation of the molecular causes of PDAC has enabled the provision of secondary screening for PDAC in conditions such as HP. This review is concerned with the molecular pathogenesis of PDAC and the application of this basic scientific understanding into state-of-the-art clinical practice.

Carcinoma, Pancreatic Ductal↗
PubMedDate not supplied

Health assessment for partners of pregnant women: a pilot study of four survey methods.

BACKGROUND: Health assessment for partners of pregnant women has not been routinely offered. Work in the area of smoking cessation suggests that a partner's health habits have a strong influence on the health habits of a pregnant woman. Smoking, alcohol abuse, depression, battering, and household firearms cab adversely affect the health of the expectant mother and the infant. METHODS: Four methods of partner assessment were pilot tested: office visit with a family physician, office visit with a registered nurse, telephone survey conducted by the registered nurse, and mailed questionnaire. Written feedback and referrals were provided to all study participants, and verbal feedback and referrals were provided to those who completed in-person or telephone interviews. A chart review was conducted to determine participation bias. RESULTS: Thirty-five pregnant women and 25 partners participated in the study. Self-administered questionnaires and telephone interviews were preferred by study participants. The study group was healthier than the general population. Five partners reported troublesome drinking behavior, and 1 reported smoking two packs of cigarettes per day. CONCLUSIONS: health assessment of partners of pregnant women seems promising for uncovering health problems that would be likely to have an adverse impact on the health of the family. Further development of assessment and intervention strategies is needed.

Adult↗